Not Applicable
This invention relates to a printhead chip for an ink jet printhead. More particularly, this invention relates to a printhead chip that incorporates rectilinear ink ejection components.
The following applications are incorporated by reference:
As set out in the above referenced applications/patents, the Applicant has spent a substantial amount of time and effort in developing printheads that incorporate micro electromechanical system (MEMS)xe2x80x94based components to achieve the ejection of ink necessary for printing.
As a result of the Applicant""s research and development, the Applicant has been able to develop printheads having one or more printhead chips that together incorporate up to 84 000 nozzle arrangements. The Applicant has also developed suitable processor technology that is capable of controlling operation of such printheads. In particular, the processor technology and the printheads are capable of cooperating to generate resolutions of 1600 dpi and higher in some cases. Examples of suitable processor technology are provided in the above referenced patent applications/patents.
The Applicant has overcome substantial difficulties in achieving the necessary ink flow and ink drop separation within the ink jet printheads.
As can be noted in the above referenced patents/patent applications, a number of printhead chips developed by the Applicant include a structure that defines an ink ejection port. The structure is displaceable with respect to the substrate to eject ink from a nozzle chamber. This is a result of the displacement of the structure reducing a volume of ink within the nozzle chamber. A particular difficulty with such a configuration is achieving a sufficient extent and speed of movement of the structure to achieve ink drop ejection. On the microscopic scale of the nozzle arrangements, this extent and speed of movement can be achieved to a large degree by ensuring that movement of the ink ejection structure is as efficient as possible.
The Applicant has conceived this invention to achieve such efficiency of movement.
According to the invention, there is provided a printhead chip for an ink jet printhead, the printhead chip comprising
a substrate; and
a plurality of nozzle arrangements that are positioned on the substrate, each nozzle arrangement comprising
a nozzle chamber structure that is positioned on the substrate to define a nozzle chamber;
an ink ejection member that is displaceable with respect to the nozzle chamber structure to eject ink from the nozzle chamber; and
at least two actuators that are operatively engaged with the ink ejection member to displace the ink ejection member, the actuators being configured and connected to the ink ejection member to impart substantially rectilinear movement to the ink ejection member.
The ink ejection member may define a roof of the nozzle chamber and an ink ejection port. The actuators may be configured so that the ink ejection member is displaced towards and away from the substrate so that a volume of the nozzle chamber is reduced and subsequently enlarged resulting in the ejection of a drop of ink from the ink ejection port.
The printhead chip may be the product of an integrated circuit fabrication technique.
The substrate may incorporate CMOS drive circuitry. Each actuator may be connected to the CMOS drive circuitry.
A number of actuators may be positioned in a substantially rotationally symmetric manner about each ink ejection member.
Each nozzle arrangement may include a pair of substantially identical actuators, one actuator positioned on each of a pair of opposed sides of the ink ejection member.
Each ink ejection member may further define sidewalls that depend from the roof. The sidewalls may be dimensioned to bound the nozzle chamber structure.
The nozzle chamber structure may define an ink displacement formation that is spaced from the substrate and faces the roof. The ink displacement formation may define an ink displacement area that is dimensioned to facilitate ejection of ink from the ink ejection port, when the ink ejection member is displaced towards the substrate.
The substrate may define a plurality of ink inlet channels, one ink inlet channel opening into each respective nozzle chamber at an ink inlet opening.
The ink inlet channel of each nozzle arrangement may open into the nozzle chamber in substantial alignment with the ink ejection port. The nozzle chamber structure may be positioned about the ink inlet opening.
Each actuator may be in the form of a thermal bend actuator. Each thermal bend actuator may be anchored to the substrate at one end and movable with respect to the substrate at an opposed end. Further, each thermal bend actuator may have an actuator arm that bends when differential thermal expansion is set up in the actuator arm. Each thermal bend actuator may be connected to the CMOS drive circuitry to bend towards the substrate when the thermal bend actuator receives a driving signal from the CMOS drive circuitry.
Each nozzle arrangement may include at least two coupling structures, one coupling structure being positioned intermediate each actuator and the ink ejection member. Each coupling structure may be configured to accommodate both arcuate movement of said opposed end of each thermal bend actuator and said substantially rectilinear movement of the ink ejection member.
The ink ejection member and the nozzle chamber structure may be shaped so that, when ink is received in the nozzle chamber, the ink ejection member, the nozzle chamber structure and the ink define a fluidic seal to inhibit ink from leaking out of the nozzle chamber between the nozzle chamber structure and the ink ejection member.